The present invention relates to a process of forming a multi-layer pad of a non-woven fiber batt and a foam layer having conforming convoluted surfaces and to a multi-layer pad incorporating a non-woven fiber batt and foam layer.
Mattresses and cushions for sofas, loveseats, chairs and other upholstery products generally comprise filler materials, batts, and foams, among other layering materials, for achieving a range of comfort, loft and durability. There are a number of advantages to be achieved by the construction of batts from synthetic, staple fiber material for use in mattresses and upholstery cushions. Such fibers are inherently lightweight and therefore easy to ship, store and manipulate during fabrication. These fibers are also generally less moisture absorbent than natural fibers such as cotton, or cellulosic based synthetic fibers such as rayon. Therefore, products made from these fibers can be maintained in a more hygienic condition and dried with much less expenditure of energy. When subjected to open flame, many of these fibers also tend to melt and drip rather than burn. While some of these fibers give off toxic fumes, the escape of such fumes has been avoided or minimized by encapsulating the batt in a fire retardant or relatively air impermeable casing. In contrast, fibers such as cotton burn rapidly at high heat and generate dense smoke.
Synthetic fiber batts have been used in mattresses and upholstery cushions since batts maintain their comfort characteristics over time. Traditional batts having desired comfort and height characteristics may generally be too stiff to allow a mattress or futon to be easily rolled for storage or folded into a sofa. As disclosed in U.S. Pat. No. 4,668,562, a batt would be required to create a mattress having the desired comfort characteristics.
Foam materials, in combination with fiber layers, have also been used in the construction of mattresses and upholstery cushions. As disclosed in U.S. Pat. No. 5,317,768, the entire disclosure of which is incorporated herein by reference, an upper surface positioned on top of the general coil structure of a mattress includes a first layer of cover or ticking, a second layer of fiber or filler material, a third layer of a foam having a convoluted surface which faces the second layer, and a fourth layer of backing material. All four layers are stitched together in a quilt pattern.
Futon furniture in recent years has become a popular alternative to standard upholstered furniture. Futon sofas, loveseats and chairs can be repositioned so that the furniture can be used as a bed. Traditionally, polyurethane foam has been combined with other types of cushioning materials such as cotton batting, latex rubber, and various man-made fiber products in order to impart the desired comfort characteristics to a final product. With time and use, the various types and combinations of materials take on different degrees of set as a result of compression from the weight of a human body. As is often the case with the softer materials, the final product will take more set over time with continued use. The more set the product takes over time, the more comfort, flexibility and height is lost from the product. It is desirable to bend, fold and/or roll up a futon mattress to be used as a sofa or for storage when the futon is not used as a flat sleep surface. Yet, when the futon is used as a sleep surface it must be stiff enough to span slats in a bed frame. Preferably, the material used in making the futon would take on little or no set.
As disclosed in U.S. patent application Ser. No. 09/363,726, entitled Convoluted Surface Fiber Pad, having as co-inventor Steven Eugene Ogle (the same inventor here) and filed on or about Jul. 29, 1999, now U.S. Pat. No. 6,500,292, the entire disclosure of which is incorporated herein by reference, a non-woven fiber pad has a convoluted surface and an integral relatively thin but stiff base formed from a non-woven fiber batt. The batt is introduced between a pair of counter-rotating drums, at least one of which has a convoluted surface. As the fiber batt is drawn between the counter-rotating drums, the convolutions upon the surface of at least one roller compresses the surface of the non-woven batt in frictional engagement therewith to a greater or lesser degree depending on the degree of surface relief of the roller convolutions. A heated wire is placed generally parallel to and between the pair of drums so that as the non-woven batt is drawn between the drums and is compressed by the drum convolutions, the heated wire cuts through the non-woven batt creating a cut-pattern generally mirroring the convolutions on the surface of the drum compressing the non-woven batt. That is, where a drum convolution compresses the batt in the vicinity of the heated wire, the wire passes through the batt at a point nearer to the batt surface which is in contact with the drum convolution.
In accordance with the present invention, there is provided a novel process for forming a multi-layer pad of a non-woven fiber batt layer and a foam layer having conforming convoluted surfaces. The novel multi-layer pad has improved compression and loft maintenance which resists permanent set over time. Further, the pad of the present invention allows lower density foam and fiber to be used while achieving improved comfort, loft and compression characteristics.
The process of forming a non-woven fiber batt layer and a foam layer having conforming convoluted surfaces comprises transporting each layer along its longitudinal dimension while compressing each layer along its lateral dimension. Concomitantly with compression, each layer is cut tranversely along its lateral dimension to separate each layer into an upper segment and a lower segment and to provide conforming convoluted surfaces between the segments of each layer.
In the preferred embodiment of the present invention, each of the non-woven fiber batt layer and the foam layer is transported by a conveyor belt to a first and a second pair of counter rotating drums, respectively, for compressing each layer. Further, at least one of each pair of drums has a convoluted surface having a raised pattern thereon. The pattern is generally a plurality of upstanding projections and depressions, and may include a plurality of pegs, straight edges or waved edges. As each layer is drawn between its pair of counter rotating drums, the convolutions on the drum surface compress the corresponding fiber or foam layer toward the opposite drum. A heated cutter is positioned generally parallel to and between each pair of drums for cutting each layer into an upper segment and a lower segment. Each heated cutter cuts through its corresponding layer material creating a cut pattern of upstanding projections and depressions which generally correspond to the convolutions on the surface of the drum compressing the layer. Further, because the cutter is heated, the fiber layer and the foam layer melt at their surfaces during the cutting operation and bond to adjacent fibers and foam cells, respectively, as their melted surfaces cools, creating a skin that retains the convoluted pattern.
The process of the present invention further comprises conforming the convoluted surface of the non-woven fiber batt layer with the convoluted surface of the foam layer. Preferably, the first pair of drums for compressing the non-woven fiber batt layer is aligned substantially above the second pair of drums for compressing the foam layer. Upon cutting the batt layer into upper and lower segments and convoluting their surfaces, the batt segments are conveyed in relatively opposite and substantially horizontal directions with their convoluted surfaces facing downward. Similarly cutting the foam layer into upper and lower segments and convoluting their surfaces, the foam segments are also conveyed in relatively opposite and substantially horizontal directions. However, the convoluted surfaces of the foam segments are facing upward. The downward facing batt segment convoluted surface is aligned with the upward facing foam segment convoluted surface so that the projections of the batt segment convoluted surface project into the corresponding depressions of the foam segment convoluted surface, while the projections of the foam segment convoluted surface project into the corresponding depressions of the batt segment convoluted surface.